I don't know if the power supply kit isolates gnd between input and output, but if it doesn't then the current display will be incorrect; the volt/current meter needs a completely isolated supply to what it is measuring. But you can get a DC/DC converter that will do this for a couple of dollars. Also, it's probably a _lot_ safer just to use an old laptop Power supply to handle the high voltage/ac stage, then handle the low voltage side with your own stuff.